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A123 Systems shows off new cell design for Chevy Volt
by Sam Abuelsamid
At the twenty-third Electric Vehicle Symposium in Anaheim, CA this week, Massachusetts
based battery supplier A123 Systems shows off its new prismatic lithium-iron-phosphate
cell for the first time. The new cell packaging has been developed for the General Motors' E-Flex development
program that includes the 2011 Chevrolet Volt.
A123 is partnering with Continental Automotive Systems as one of two teams with
development contracts to supply battery packs for the new range-extended electric
vehicle that was first shown at the 2007 Detroit Auto Show. A123 is applying their nano-phosphate technology to create cells that Continental
will integrate into battery packs for bench testing and installation into prototype
vehicles.
For an automotive application, the range of possible operating environments ranges
from -40F up to 120F or more. A123 Vice-President Ric Fulop explained that in a large pack, such as those
needed for a car, it's important to maintain a consistent temperature across the
entire pack. This is necessary to ensure the safety and longevity of the pack as well as
the performance during the life of the vehicle.
Previous A123 cells for non-automotive applications have been cylindrical, but
the new design is rectangular. The older applications have been air cooled and used relatively few cells. The
packs for the Volt are planned to be liquid cooled to maximize the robustness
of the system in the wide ranging automotive environment. The new cells provide more surface area that's in contact with the cooling system. That will allow each individual cell to be kept at its optimum temperature throughout
the length and width of the pack.
Continental is handling the integration of the cells into battery packs for vehicle
installation. Continental is due to deliver its first pack to the GM Tech Center
in Warren, MI later this month. Compact Power, a division of Korean firm LG Chem
delivered its first pack at the end of October with a second pack arriving in
late November.
In a recent interview, GM's Director of Energy Storage Systems Denise Gray indicates
that the GM battery team hopes to soon be on a regular schedule of pack deliveries. The first packs are being used for bench testing and characterization. The data derived from these tests will be used to calibrate the state of charge
and health models for the batteries. Those models are an integral part of managing the battery charge and discharge
during vehicle operation.
GM is building the first test mules for the Volt program and battery packs will
be installed in those vehicles early in 2008. The first batch of test vehicles will use the larger 16 kWh battery packs and
the gasoline/E85 engine range extender. The fuel cell variant with an 8 kWh pack is also being developed in parallel. The current plan is for the Volt with the internal combustion range extender
to enter production late in 2010 and GM representatives have said that either
or both of the current development suppliers may end up providing packs for the
production cars.
DECEMBER 2007 |
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